The invention relates generally to subterranean wells used for hydrocarbon extraction or other purposes, and more specifically to a method for removing at least a portion of an object in an annulus formed between an external surface of a tubular element and a wall surface. More specifically, a method for removing an annulus packer, of the swellable type or the foam type, from an annulus in a wellbore is described.
Annulus packers are commonly used to seal off portions of the annulus between a pipe (e.g. a production tubing) and the wellbore. One application is described in Norwegian Patent No. 312478, wherein an annular packer is arranged on the outside of a production tubing. The annular packer comprises a core having an elastic polymer. The packer swells by absorption of hydrocarbons and expands to seal the annular space between a production tubing and a well wall.
A person skilled in the art will also be familiar with other swellable packers, such as those which swell in water or water-based fluids, or foam type packers, such as those which expand in the presence of gas. Swellable packers in general are used to seal off portions of an annulus between a pipe and a wellbore wall.
Sometimes a need arises for pulling the pipe or tubing (removal from, or displacement in, the well). With systems employing mechanical or inflatable annulus packers, this pulling is achieved by mechanically releasing or deflating the packers. However, pipes, tubing, etc., set with swellable packers or foam type packers are essentially permanently set.
Thus, in order to pull a pipe or tubing, etc., set with swellable packers or foam type packers, known techniques include, e.g., a mechanical milling process to remove the packer. This is an iterative process, requiring several runs. For example, a first run will be necessary in order to cut the pipe; then an overshot mill is run, before the pipe is cut below the packer in a third run. The procedure must be repeated for each packer in order to retrieve the pipe. One can understand how the pulling operation therefore consumes considerable rig time and entails a considerable cost impact.
Various methods and systems exist for performing downhole cutting operations, either in subterranean formations, packers or tubing.
RU 2123106 discloses a method for cutting perforation channels using abrasive fluids.
U.S. Pat. No. 4,296,822 discloses a multi-purpose fluid flow assisted downhole tool, that is adapted for attachment to the lower end of the pipe string to be extended into a well bore, and capable of cutting sample cores from subsurface formations.
U.S. Pat. No. 4,450,907 discloses a tool having a special overshot which attaches to a cut-off tubing on a packer. A method and apparatus for removing precipitated solids from above a packer in a well bore to the extent necessary to enhance the removal of the packer. The overshot comprises an opening which allows the tubing string to be passed through and into the annulus.
GB 916579 discloses a milling apparatus for removing a resilient packer from a well bore.
U.S. Pat. No. 4,428,430 discloses a method and apparatus for perforating a circulation port through the sidewall of a drill collar to provide circulation of weighted drilling fluid down through the drill string and back up the well annulus. A chemical reactant wireline perforating tool is lowered to a designated position within a drill collar, and a single chemical flow jet forces a chemical reactant through the jet under high pressure and at high temperature to react with the drill collar metal and thereby remove a portion of the metal with the remaining metal defining a fluid circulation port through the drill collar wall. Fluid is subsequently pumped through the port to establish circulation. The apparatus includes a tool body defining a single fluid flow jet, pressure actuated slips with the body to support the body against movement within the drill pipe, a body of chemical within the tool, a reaction section to heat the chemical, a pressure responsive decentralizing mechanism to position to the tool and thereby place the flow jet into position to direct the chemical directly onto the interior wall of the drill collar.
U.S. Pat. No. 5,494,103 discloses a well jetting apparatus for use in fracturing a well. Fracture initiation is provided by forming openings through a well casing and then forming fan-shaped slots in the formation surrounding the casing. The slots are formed by the jetting apparatus which has at least one hydraulic jet. The jetting apparatus may be used in any well configuration.
Therefore, a need exists for a method whereby pipes or tubing set with swellable packers or foam type packers may be pulled easier and faster than with the known methods.